scholarly journals Proposals for Nothofagus antarctica diameter growth estimation: simple vs. global models

2014 ◽  
Vol 60 (No. 8) ◽  
pp. 307-317 ◽  
Author(s):  
H. Ivancich ◽  
G.J. Martínez Pastur ◽  
M.V. Lencinas ◽  
J.M. Cellini ◽  
P.L. Peri
Keyword(s):  
Tree Growth ◽  
Growth Models ◽  
Site Quality ◽  
Diameter Growth ◽  
Wide Range ◽  
Nothofagus Antarctica ◽  
Simple Growth ◽  
Simple Equations ◽  
Diameter Growth Models ◽  
Stand Conditions

Tree growth is one of the main variables needed for forest management planning. The use of simple models containing traditional equations to describe tree growth is common. However, equations that incorporate different factors (e.g. site quality of the stands, crown classes of the trees, silvicultural treatments) may improve their accuracy in a wide range of stand conditions. The aim of this work was to compare the accuracy of tree diameter growth models using (i) a family of simple equations adjusted by stand site quality and crown class of trees, and (ii) <br /> a unique global equation including stand and individual tree variables. Samplings were conducted in 136 natural even-aged Nothofagus antarctica (Forster f.) Oersted stands in Southern Patagonia (Argentina) covering age (20&ndash;200 years), <br /> crown class and site quality gradients. The following diameter growth models were fitted: 16 simple equations using two independent variables (age and one equation for each stand site quality or crown class) based on Richards model, plus a unique global equation using three independent variables (age, stand site quality and crown class). Simple equations showed higher variability in their accuracy, explained between 54% and 92% of the data variation. The global model presented similar accuracy like the better equations of the simple growth models. The unification of the simple growth models into a unique global equation did not greatly improve the accuracy of estimations, but positively influenced the biological response of the model. Another advantage of the global equation is the simple use under a wide range of natural stand conditions. The proposed global model allows to explain the tree growth of N. antarctica trees along the natural studied gradients. &nbsp; &nbsp;

scholarly journals Evaluation of Individual Distance-Independent Diameter Growth Models for Japanese Cedar (Cryptomeria japonica) Trees under Multiple Thinning Treatments

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 344 ◽  
Author(s):  
Keiko Fukumoto ◽  
Tomohiro Nishizono ◽  
Fumiaki Kitahara ◽  
Kazuo Hosoda
Keyword(s):  
Forest Management ◽  
Tree Growth ◽  
Cryptomeria Japonica ◽  
Growth Models ◽  
Japanese Cedar ◽  
Diameter Growth ◽  
Model Accuracy ◽  
Thinning Intensity ◽  
Diameter Growth Models

Understanding the tree growth process is essential for sustainable forest management. Future yields are affected by various forest management regimes such as thinning; therefore, accurate predictions of tree growth are needed under various thinning intensities. This study compared the accuracy of individual-level distance-independent diameter growth models constructed for different thinning intensities (thinning intensity-dependent multiple models: TDM model) against the model designed to include all thinning intensities (thinning intensity-independent single model: TIS model) to understand how model accuracy is affected by thinning intensity. We used long-term permanent plot data of Japanese cedar (Cryptomeria japonica) stands in Japan, which was gathered from four plots where thinning was conducted at different thinning intensities: (1) intensive (41% and 38% of trees removed at 25 and 37 years old, respectively), (2) moderate (38% and 34%), (3) light (32% and 34%), and (4) no thinning. First, we specified high interpretability distance-independent competition indices, and we compared the model accuracy both in TDM and TIS models. The results show that the relative spacing index was the best competition index both in TDM and TIS models across all thinning intensities, and the differences in the RMSE (Root mean square error) and rRMSE (relative RMSE) in both TDM and TIS models were 0.001–0.01 cm and 0.2–2%, respectively. In the TIS model, rRMSE varied with thinning intensity; the rRMSE was the lowest for moderate thinning intensity (45.8%) and the highest for no thinning (59.4%). In addition, bias values were negative for the TIS model for all thinning intensities. These results suggest that the TIS model could express diameter growth regardless of thinning intensities. However, the rRMSE had varied with thinning intensity and bias had negative values in the TIS model. Therefore, more model improvements are required for accurate predictions of long-term growth of actual Japanese cedar stands.

Suitability of two methods of evaluating site quality for sugar maple in central Ontario

2006 ◽  
Vol 82 (5) ◽  
pp. 733-744 ◽  
Author(s):  
Nicholas J Buda ◽  
Jian R Wang
Keyword(s):  
Sugar Maple ◽  
Quality Evaluation ◽  
Growth Models ◽  
Site Index ◽  
Height Growth ◽  
Site Quality ◽  
Dominant Height ◽  
Index Site ◽  
Species Mixture ◽  
Stand Conditions

Stem analyses data collected in central Ontario stands were used to develop site index (height and age) and site form (height and diameter) models and curves for sugar maple. The suitability of both methods for evaluating sugar maple site productivity was examined. Two different equation forms were evaluated for both site index and site form models. A common modification of Richard's (1959) equation was most suitable for predicting dominant height at index age (site index) and reference diameter (site form). Potential effects of species mixture on sugar maple site index were examined. We found no significant effects on sugar maple height growth and site index in mixed stand conditions common in the region when compared to pure stands. The potential of site form as an alternative to site index was investigated through correlation analyses with site index and other site variables known to influence sugar maple height growth. Site form was not related to site index, nor any site variables related to sugar maple height growth. It is therefore inadequate for evaluating sugar maple site quality. We recommend height growth models and site index curves developed in this study be used to replace those from other regions currently used in central Ontario. Key words: site index, site form, sugar maple, site quality evaluation, mixedwood, uneven-aged

scholarly journals Individual-Tree Diameter Growth Models for Mixed Nothofagus Second Growth Forests in Southern Chile

Forests ◽  
2017 ◽  
Vol 8 (12) ◽  
pp. 506 ◽  
Author(s):  
Paulo Moreno ◽  
Sebastian Palmas ◽  
Francisco Escobedo ◽  
Wendell Cropper ◽  
Salvador Gezan
Keyword(s):  
Growth Models ◽  
Diameter Growth ◽  
Southern Chile ◽  
Individual Tree ◽  
Tree Diameter ◽  
Second Growth ◽  
Diameter Growth Models

scholarly journals Individual Tree Diameter Growth Models of Larch–Spruce–Fir Mixed Forests Based on Machine Learning Algorithms

Forests ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 187 ◽  
Author(s):  
Qiangxin Ou ◽  
Xiangdong Lei ◽  
Chenchen Shen
Keyword(s):  
Machine Learning ◽  
Tree Growth ◽  
Growth Models ◽  
Tree Size ◽  
Diameter Growth ◽  
Individual Tree ◽  
Mixed Forests ◽  
Tree Diameter ◽  
Individual Tree Growth ◽  
The Individual

Individual tree growth models are flexible and commonly used to represent growth dynamics for heterogeneous and structurally complex uneven-aged stands. Besides traditional statistical models, the rapid development of nonparametric and nonlinear machine learning methods, such as random forest (RF), boosted regression tree (BRT), cubist (Cubist) and multivariate adaptive regression splines (MARS), provides a new way for predicting individual tree growth. However, the application of these approaches to individual tree growth modelling is still limited and short of a comparison of their performance. The objectives of this study were to compare and evaluate the performance of the RF, BRT, Cubist and MARS models for modelling the individual tree diameter growth based on tree size, competition, site condition and climate factors for larch–spruce–fir mixed forests in northeast China. Totally, 16,619 observations from long-term sample plots were used. Based on tenfold cross-validation, we found that the RF, BRT and Cubist models had a distinct advantage over the MARS model in predicting individual tree diameter growth. The Cubist model ranked the highest in terms of model performance (RMSEcv [0.1351 cm], MAEcv [0.0972 cm] and R2cv [0.5734]), followed by BRT and RF models, whereas the MARS ranked the lowest (RMSEcv [0.1462 cm], MAEcv [0.1086 cm] and R2cv [0.4993]). Relative importance of predictors determined from the RF and BRT models demonstrated that the competition and tree size were the main drivers to diameter growth, and climate had limited capacity in explaining the variation in tree diameter growth at local scale. In general, the RF, BRT and Cubist models are effective and powerful modelling methods for predicting the individual tree diameter growth.

scholarly journals Development of Diameter Growth Models by Thinning Intensity of Planted Quercus glauca Thunb. Stands

2021 ◽  
Vol 24 (6) ◽  
pp. 629-638
Author(s):  
Su Young Jung ◽  
Kwang Soo Lee ◽  
Hyun Soo Kim
Keyword(s):  
Mean Squared Error ◽  
Growth Models ◽  
Diameter Growth ◽  
Least Squares Regression ◽  
Permanent Sample Plots ◽  
Thinning Intensity ◽  
Squared Error ◽  
Quercus Glauca ◽  
The Mean ◽  
Diameter Growth Models

Background and objective: This study was conducted to develop diameter growth models for thinned Quercus glauca Thunb. (QGT) stands to inform production goals for treatment and provide the information necessary for the systematic management of this stands.Methods: This study was conducted on QGT stands, of which initial thinning was completed in 2013 to develop a treatment system. To analyze the tree growth and trait response for each thinning treatment, forestry surveys were conducted in 2014 and 2021, and a one-way analysis of variance (ANOVA) was executed. In addition, non-linear least squares regression of the PROC NLIN procedure was used to develop an optimal diameter growth model.Results: Based on growth and trait analyses, the height and height-to-diameter (H/D) ratio were not different according to treatment plot (p > .05). For the diameter of basal height (DBH), the heavy thinning (HT) treatment plot was significantly larger than the control plot (p < .05). As a result of the development of diameter growth models by treatment plot, the mean squared error (MSE) of the Gompertz polymorphic equation (control: 2.2381, light thinning: 0.8478, and heavy thinning: 0.8679) was the lowest in all treatment plots, and the Shapiro-Wilk statistic was found to follow a normal distribution (p > .95), so it was selected as an equation fit for the diameter growth model.Conclusion: The findings of this study provide basic data for the systematic management of Quercus glauca Thunb. stands. It is necessary to construct permanent sample plots (PSP) that consider stand status, location conditions, and climatic environments.

Predicting past and future diameter growth for trees in the northeastern United States

2006 ◽  
Vol 36 (6) ◽  
pp. 1551-1562 ◽  
Author(s):  
James A Westfall
Keyword(s):  
United States ◽  
Growth Models ◽  
Error Function ◽  
Forest Growth ◽  
Diameter Growth ◽  
Northeastern United States ◽  
Mixed Effects Modeling ◽  
Acquisition Costs ◽  
Species Groups ◽  
Diameter Growth Models

Tree diameter growth models are widely used in forestry applications, often to predict tree size at a future point in time. Also, there are instances where projections of past diameters are needed. A relative diameter growth model was developed to allow prediction of both future and past growth rates. Coefficients were estimated for 15 species groups that cover most tree species in the northeastern United States. Application of the model to independent data generally showed slight underprediction of growth, although the bias was negligible. Correlated observations were accounted for via a mixed-effects modeling approach, and an error function was specified to address heterogeneous variance. The models use a minimum amount of field-collected data, thus keeping data acquisition costs low and facilitating use in many forest growth applications.

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